Here's a card I made and sent out to my nieces and nephews who start back to school next week. I created it on the computer and printed them on white cardstock. The crayons pull out the top of the box and I wrote messages on the back of them. I even created a little "UPC" on the back with the date I made them.
A few years ago I used this picture of my dog with a backpack on and had it made into postcards to send.
Another year I used this clipart and mounted it on red cards and sent them out.